import asyncio, logging

import aiomysql

def log(sql, args=()):
    logging.info('SQL: %s' % sql)

# 创建连接池
async def create_pool(loop, **kw):
    logging.info('create database connect pool...')
    global __pool
    _pool = await aiomysql.create_pool(
        host = kw.get('host', '127.0.0.1'),
        port = kw.get('port', 3306),
        user = kw['user'],
        password = kw['password'],
        db = kw['db'],
        charset=kw.get('charset','utf8'),
        autocommit=kw.get('autocommit', True),
        maxsize=kw.get('maxsize', 10),
        minsize=kw.get('minsize', 1),
        loop=loop
    )

# SELECT查询语句
async def select(sql, args, size=None):
    log(sql, args)
    global __pool
    async with __pool.get() as conn:
        async with conn.cursor(aiomysql.DictCursor) as cur:
            await cur.execute(sql.replace('?','%s'), args or ())
            if size:
                rs = await cur.fetchmany(size)
            else:
                rs = await cur.fetchall()
        logging.info('rows return: %s' % len(rs))
        return rs

# EXECUTE执行语句
async def execute(sql, args, autocommit=True):
    log(sql)
    async with __pool.get() as conn:
        if not autocommit:
            await conn.begin()
        try:
            async with conn.cursor(aiomysql.DictCursor) as cur:
                await cur.execute(sql.replace('?', '%s'), args)
                affected = cur.rowcount
            if not autocommit:
                await conn.commit()
        except BaseException as e:
            if not autocommit:
                await conn.rallback()
            raise
        return affected




def create_args_string(num):
	L = []
	for n in range(num):
		L.append('?')
	return ', '.join(L)

class Field(object):
	"""docstring for Field"""
	def __init__(self, name, column_type, primary_key, default):
		self.name = name
		self.column_type = column_type
		self.primary_key = primary_key
		self.default = default
	def __str__(self):
		return '<%s, %s:%s>' % (self.__class__.__name__, self.column_type, self.name)

class  StringField(Field):
	"""docstring for  StringField"""
	def __init__(self, name=None, primary_key=False, default=None, ddl='varchar(100)'):
		super().__init__(name, ddl, primary_key, default)

class BooleanField(Field):
	"""docstring for BooleanField"""
	def __init__(self, name=None, default=False):
		super().__init__(name, 'boolean', False, default)

class IntegerField(Field):
	"""docstring for IntegerField"""
	def __init__(self, name=None, primary_key=False, default=0):
		super().__init__(name, 'bigint', primary_key, default)

class FloatField(Field):
	"""docstring for FloatField"""
	def __init__(self, name=None, primary_key=False, default=0.0):
		super().__init__(name, 'real', primary_key, default)

class TextField(Field):
	"""docstring for TextField"""
	def __init__(self, name=None, default=0):
		super().__init__(name, 'bigint', False, default)




class ModelMetaclass(object):
	"""docstring for ModelMetaclass"""

	def __new__(cls, name, bases, attrs):
		if name=='Model':
			return type.__new__(cls, name, bases, attrs)
		tableName = attrs.get('__table__', None) or name
		logging.info('found mode: %s (table: %s)' % (name, tableName))
		mappings = dict()
		fields = []
		primaryKey = None
		for k,v in attrs.items():
			if isinstance(v, Field):
				logging.info('  found mapping: %s ==> %s' % (k, v))
				mappings[k] = v
				if v.primary_key:
					if primaryKey:
						raise StandardError('Duplicate primary key for field %s' % k)
					primaryKey = k
				else:
					fields.append(k)
		if not primaryKey:
			raise StandardError('Primary key not found')
		for k in mappings.keys():
			attrs.pop(k)
		escaped_fields = list(map(lambda f: '`%s`' % f, fields))
		attrs['__mappings__'] = mappings
		attrs['__table__'] = tableName
		attrs['__primary_key__'] = primaryKey
		attrs['__fields__'] = fields
		attrs['__select__'] = 'select `%s`, `%s` from `%s`' % (primaryKey, ', '.join(escaped_fields), tableName)
		attrs['__insert__'] = 'insert into `%s` (`%s`, `%s`) values `%s`' % (tableName, ', '.join(escaped_fields), primaryKey, create_args_string(len(escaped_fields)+1) )
		attrs['__update__'] = 'update `%s` set %s where `%s`=?' % (tableName, ', '.join(map(lambda f: '`%s`=?' % (mappings.get(f).name or f), fields)), primaryKey)
		attrs['__delete__'] = 'delete from `%s` where `%s` = ?' % (tableName, primaryKey)
		return type.__new__(cls, name, bases, attrs)

class Model(dict):
    __metaclass__ = ModelMetaclass
    """docstring for Model"""
    def __init__(self, **kw):
        super(Model, self).__init__(**kw)
    def __getattr__(self, key):
        try:
            return self[key]
        except KeyError:
            raise AttributeError(r" 'Model' object has no attribute '%s' " % key)

    def __setattr__(self, key, value):
        self[key] = value

    def getValue(self, key):
        return getattr(self, key, None)

    def getValueOrDefault(self, key):
    	value = getattr(self, key, None)
    	if value is None:
    		field = self.__mappings__[key]
    		if field.default is not None:
    			value = field.default() if callable(field.default) else field.default
    			logging.debug('using default value for %s: %s' % (key, str(value)))
    			setattr(self, key, value)
    	return value

    @classmethod
    async def findAll(cls, where=None, args=None, **kw):
    	' find objects by where clause. '
    	sql = [cls.__select__]
    	if where:
    		sql.append('where')
    		sql.append(where)
    	if args is None:
    		args = []
    	orderBy = kw.get('orderBy', None)
    	if orderBy:
    		sql.append('order by')
    		sql.append(orderBy)
    	limit = kw.get('limit', None)
    	if limit is not None:
    		sql.append('limit')
    		if isinstance(limit, int):
    			sql.append('?')
    			args.append(limit)
    		elif isinstance(limit, tuple) and len(limit) == 2:
    			sql.append('?, ?')
    			args.extend(limit)
    		else:
    			raise ValueError('Invalid limit value: %s' % str(limit))
    	rs = await select(' '.join(sql), args)
    	return [cls(**r) for r in rs]

    @classmethod
    async def findNumber(cls, selectField, where=None, args=None):
    	' find number by select and where. '
    	sql = ['select %s _num_ from `%s`' % (selectField, cls.__table__)]
    	if where:
    		sql.append('where')
    		sql.append(where)
    	rs = await select(' '.join(sql), args, 1)
    	if len(rs) == 0:
    		return None
    	return rs[0]['_num_']

    @classmethod
    async def find(cls, pk):
    	' find object by primary key. '
    	rs = await select('%s where `%s`=?' % (cls.__select__, cls.__primary_key__), [pk], 1)
    	if len(rs) == 0:
    		return None
    	return cls(**rs[0])

    async def save(self):
    	args = list(map(self.getValueOrDefault, self.__fields__))
    	args.append(self.getValueOrDefault(self.__primary_key__))
    	rows = await execute(self.__insert__, args)
    	if rows != 1:
    		logging.warn('failed to insert record: affected rows: %s' % rows)

    async def update(self):
    	args = list(map(self.getValue, self.__fields__))
    	args.append(self.getValue(self.__primary_key__))
    	rows = await execute(self.__update__, args)
    	if rows != 1:
    		logging.warn('failed to update by primary key: affected rows %s' % rows)

    async def remove(self):
        args = [self.getValue(self.__primary_key__)]
        rows = await execute(self.__delete__, args)
        if rows != 1:
            logging.warn('failed to remove by primary key: affected rows %s' % rows)






		
		
						
		